Two materials can be joined together by a variety of different techniques, such as welding, adhesives, or fastening. Often times, materials are fastened together by one or more “fasteners”. In this context, a fastener is a piece of hardware that mechanically affixes two or more materials together. Known fasteners include nails, bolts, screws, and rivets. When joining materials with a fastener, it can be desirable to simultaneously distribute load. Known fastener and load distributor combinations include grommets and bushings.
Fastening composite materials creates a unique set of problems related to the thermal properties of the joined materials and the fastener system. Composite materials are desirable due to high strength-to-weight ratios and high temperature resistance, which allows them to be exposed to extreme environments. Composite materials, however, experience significant stresses when joined to metals with significantly different coefficients of thermal expansion. The disparity in thermal properties between composite materials and metals may mechanically strain fasteners as well as the surrounding composite material.